Vicks VapoRub May Imperil Toddlers

Action Points

Explain to interested patients that Vicks VapoRub is widely used to relieve the symptoms of chest congestion but is not indicated for children under two.

Note that this study, in animals, suggests that the salve can increase secretion of mucus and cause inflammation, perhaps leading to respiratory distress, in children, whose airways are smaller and more vulnerable.

WINSTON-SALEM, N.C., Jan. 13 -- A popular menthol-based salve used to ease symptoms of chest congestion may be dangerous for young children, researchers here said.

In an animal study, Vicks VapoRub stimulated mucus production and airway inflammation -- effects that might have a severe impact on breathing in an infant or toddler, according to Bruce Rubin, M.D., and colleagues at Wake Forest University.

"The ingredients in Vicks can be irritants, causing the body to produce more mucus to protect the airway," Dr. Rubin said.

"Infants and young children have airways that are much narrower than those of adults, so any increase in mucus or inflammation can narrow them more severely."

The findings came after Dr. Rubin and colleagues cared for an 18-month-old girl in respiratory distress after the salve was placed under her nostrils to relieve symptoms of an upper respiratory infection.

Although the salve is not indicated for children younger than two years, caregivers sometimes ignore the advice, they said in the January issue of CHEST.

The child was admitted to a hospital, treated with supplemental oxygen, and discharged the following day. The researchers hypothesized that the salve had caused inflammation and mucociliary dysfunction, with increased mucus secretion leading to severe shortness of breath.

To test the idea, they conducted in vitro and in vivo studies of the effect of the salve on ferrets, whose airway anatomy and cellular composition is similar to humans.

In excised tracheas, the salve increased mucin secretion by 63% compared with control tissue treated with a water-based soluble jelly, a difference that was significant at P<0.01.

At the same time, the frequency of ciliary beats was reduced by 35%, compared with control tissue, a difference that was significant at P<0.042.

To test effects in living animals, the researchers caused inflammation of the airway (using a bacterial endotoxin) in one group of ferrets to simulate a respiratory infection.

The animals were intubated, and the salve was placed on the inside of the tube connector.

The researchers found:

VapoRub increased mucin secretion in the normal airway by 14% and in the inflamed airway 7.8%, but the difference did not reach statistical significance.

On the other hand, the endotoxin itself increased mucin secretion by 67% (significant at P=0.007) compared with normal airways.

The salve significantly increased (P=0.027) mucociliary transport velocity compared with those treated with the water-based jelly, regardless of inflammation.

But for the inflamed airways, the significance of the increase was P=0.007.

The researchers said the perceived benefit of the salve is thought to be the result of the menthol binding to temperature sensors and causing a cooling sensation.

The brain interprets the sensation as increased airflow although, in fact, studies have shown that the salve reduces airflow marginally even in adults.

Dr. Rubin and colleagues said the most dramatic results came from the in vitro experiments where tissue was exposed to more of the salve than is typically reached in the airway.

Despite that limitation, they said, they were able to detect "small but potentially clinically significant changes" after the ferrets inhaled the VapoRub vapors.

The finding "supports the suggestion that these changes in mucus secretion and clearance may, in part, explain what we saw in the human infant," they said.

They suggested that "this may be of little physiologic consequence in older children and adults, but in infants and small children this potentially can lead to respiratory distress."

The researchers did not report any external support for the study or any conflicts.

Reviewed by Zalman S. Agus, MD Emeritus Professor University of Pennsylvania School of Medicine

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